Frequently Asked Questions

orDrumbox-v2 is a free, open-source drum machine and step sequencer that runs in a web browser. It also sequences pitched sounds (bass lines, chords, arpeggios) with its built-in synthesizer. Work is organised in songs, which contain patterns; each pattern contains tracks, and each track plays a sound from the selected drumkit.

• Drumkit: a set of samples, each assigned to an instrument (KICK, SNARE, CHH…). Switching the drumkit changes the sounds of all tracks in the pattern.
• Instrument: the role of a sound in the kit (KICK, SNARE, etc.), used to match samples to tracks automatically.
• Track: one row of the pattern: its notes, its loop point, its sound (a sample or a synthesizer sound) and its settings (volume, pan, pitch, filter, effects, LFOs).

orDrumbox is oriented towards rhythmic and algorithmic experimentation. Several features change what a pattern plays from one loop to the next without editing it: conditional note triggers, probabilities, per-track loop points (polyrhythms), per-track variation and automatic generation.

Yes. orDrumbox is free and released under the MIT licence, which allows personal and commercial use. The source code is on GitHub.

Yes. Each note has a pitch offset (-24 to +24 semitones), so a track can play a bass line, a melody or chords with a sample or a synthesizer sound. The Bass and Chords generation buttons create these parts automatically, and the piano roll shows notes on a pitch axis.

• Pitch: set per note in the Note Editor (semitones from C3) or per track in the Track Editor; notes can also be placed in the piano roll view.
• Arpeggiator: per note, with a scale (major, minor, pentatonic, modes, blues…), a direction (up, down, updown) and a range of 0–12 notes.
• Glide: the synthesizer's slide parameter (0–500 ms) slides the pitch from one note to the next.

• Triggers and probability: a note can play only every N-th loop, with a phase offset (for example once every 4 loops), or with a probability between 0 and 1.
• Retrigger: repeats a note as 1–16 sub-hits within its step (rolls, ratchets, fills).
• Euclidean fill: adds N evenly-spaced sub-hits between a note and the next one on the track.
• Per-track timing: steps per beat (1–8), loop point and swing are set per track.
• Per-note parameters: velocity, pitch and pan are set individually for each note.
• Variation: a per-track setting that randomly adds or removes notes and changes velocity or pitch at each loop.

Each track has its own loop point, so tracks of the same pattern can loop over different lengths (for example a 3-step hi-hat loop over a 16-step kick sequence).

Tracks with different lengths shift against each other from one loop to the next, which produces polyrhythms and polymeters: the combination of tracks only repeats after several loops.

The built-in drumkits cover:

• Acoustic kits: recorded drum sets and percussion.
• Vintage and electronic kits: drum-machine style kicks, snares, hi-hats and percussion.
• 8-bit and generated kits: retro-style sounds and sounds produced by the synthesizer.

Yes. The Import Directory button of the Drumkit Manager opens a folder picker, imports the audio files it contains (.wav, .flac) as a new drumkit and matches each file to an instrument automatically.

Single files (WAV, FLAC, MP3, AAC) can also be added to a kit with + Add, or loaded on a track from the Track Editor.

In the Drumkit Manager, for each sample:

• Gain (-24 to +6 dB), Tune (-12 to +12 semitones) and Decay (0–5000 ms).
• Instrument assignment and Kit (moves the sample to another drumkit).
• Replace or Remove the sample.

For the whole kit: Auto-detect (assigns instruments to all samples) and Normalize (normalises all samples to 0 dB peak).

Import a folder of samples with Import Directory, or add files one by one with + Add. Then adjust each sample in the Drumkit Manager (gain, tune, decay, instrument) and save the kit as a .json file with ↓ Save.

Yes. The sound of each track is chosen in the Sound section of the Track Editor: either a sample from the drumkit or a sound generated by the synthesizer (3 oscillators, FM, filter, noise, ADSR envelope, 2 LFOs).

Yes. A drumkit is exported as a .json file with ↓ Save in the Drumkit Manager and imported with ↑ Load, for example to move it to another browser or share it.

All tracks feed a common master bus, set in the Output panel: pre-gain, compressor, low-cut filter (default 35 Hz), high-cut filter (default 18.5 kHz) and master volume. Each track also has its own filter, saturation, reverb and delay.

The Drum, Bass and Chords buttons generate the corresponding parts of the pattern from a genre-based song structure. A track can also be set to Auto, so that it is regenerated at each loop, and the Variation setting changes a track slightly at each loop. Generated notes can then be edited like any other note.

Yes, with a local setup. The source repository includes an MCP server (ordrumboxMcpserver.mjs) that an MCP client (Claude Desktop, Cursor…) launches with Node.js. It provides tools to create and edit patterns, tracks and notes, select kits and control playback. The list of tools is in MCP_TOOLS.md and the setup in MCP_SETUP.md.

The MCP server is not available from the online version: it requires a local copy of the repository and Node.js 18 or later.

Yes. Export WAV in the Tools panel renders the current pattern to a .wav file, repeated 1–32 times (Loops setting). The file can be used in a DAW (Ableton Live, FL Studio, Logic Pro…) or played on its own.

Yes. Export MIDI creates a standard MIDI file (SMF type 1, .mid) with one track per instrument; drum tracks use channel 10 and muted tracks are left out. MIDI files can also be imported into new patterns.

In browsers that support Web MIDI, orDrumbox can send notes to a MIDI output device and follow an external MIDI clock.

orDrumbox uses the Web Audio API (including AudioWorklet for the synthesizer) to play and process sound in the browser, without plugins. Latency and performance depend on the browser and the device.

Patterns, songs, drumkits, samples and settings are stored in the browser (IndexedDB). They can also be exported as .json files: a pattern from the Pattern Panel, a whole song from the Patterns Panel, a drumkit from the Drumkit Manager. Audio is exported as .wav.

Browser storage: data kept by the browser on this device (IndexedDB); it can be inspected and cleared from the Cache tab of the Tools panel.

Export/import: a .json file saved on your disk, which can be kept as a backup or opened in another browser.

Clearing the site data of ordrumbox.com in the browser deletes the songs, patterns and kits stored in IndexedDB. Exported .json files are not affected. To keep a song, export it with Export Song in the Patterns Panel.

Yes. orDrumbox is a Progressive Web App (PWA). On desktop (Chrome, Edge), use the install icon in the address bar; on mobile, use "Add to Home Screen" in the browser menu. Once installed, it works offline. An internet connection is required for the first load.